A retrospective study of bacteriemias due to S. pneumoniae in adults is performed, from all the cases observed in our hospital during the 1989-1990 period. We compare the clinical characteristics of the disease depending if the affected patients were infected or not by the human immunodeficiency virus (HIV). In the considered period bacteriemia due to S. pneumoniae has been diagnosed in 12 patients with HIV infection and 29 without it. Ten of the twelve patients with HIV infection (83.3%) were in Stage IV (CDC) of the disease, staying the rest in a less developed phase of the disease. Age was significantly higher in non-HIV patients (p < 0.001) and a high percentage of patients in this group (75%) showed some disease considered as predisposing to bacteriemia due to S. pneumoniae. When a respiratory foci was present, VIH positive individuals showed more frequently bilateral radiologic infiltrates and less frequently pleural effusion. Leucocyte count when diagnosis was done were significantly higher in non-HIV group. Sensibility of isolated S. pneumoniae was similar in the two groups, being the immediate mortality related with bacteriemia due to S. pneumoniae higher in the non-HIV group. In our center 29.3% of bacteriemias due to S. pneumoniae are diagnosed in patients with HIV infection. This disease in itself could constitute an added risk factor in the development of bacteriemia due to S. pneumoniae.